Lubricants are largely used in systems comprising moving mechanical parts for reducing the wear of said mechanical parts. Perfluoropolyethers have been well established in the lubrication industry in this application for over 30 years. Due to their chemical inertness, non flammability, excellent temperature-viscosity properties and high thermal and oxidative resistance, these fluids found application in specialized sectors requiring particularly severe conditions (temperature up to 300° C.) or extremely harsh environment, such as aerospace, military, oxygen and aggressive chemical handling, and the like.
Nevertheless, despite these outstanding properties of perfluoropolyethers, said perfluoropolyethers are not generally endowed with satisfactory anti-wear properties: these materials generally show wear values well above those generally obtained with hydrocarbon or synthetic oils and do not provide protection against corrosion due to their high permeability to gases and moisture.
Anti-wear additives generally employed in conventional hydrogenated lubricants cannot be used for these fluids, because of their poor solubility in perfluoropolyethers.
Thus,    Patent Citation 0001: U.S. Pat. No. 3,201,445 (E.I. DU PONT DE NEMOURS). Aug. 17, 1965. discloses cyclic phosphazenes bearing polyfluoroether alcohols moieties complying with formula here below:
wherein:                X is a halogen atom or a group of formula:        
                Y is F or CF3;        n is an integer of from 1 to 10; and        m is an integer from 2 to 3,said compounds being suitable to be used as high temperature lubricants.            Patent Citation 0002: EP 0597369 A (AUSIMONT S.P.A.). Aug. 18, 1964. discloses fully substituted phosphazenes of cyclic or linear structure complying with formula here below:
wherein:                n is 0 or 1;        m is an integer from 3 to 7;        groups A are selected from:            (i) R-Q-, in which Q is a divalent group selected from —O—, —S—, —NR1—(R1═C1-4 alkyl) and —NH—NH—; R is a C6-C12 aryl group;    (ii) Rf—CH2—O(CH2CH2O)s—, in which s=0,1 and Rf is a perfluoropolyethereal chain having molecular weight from 400 to 10 000, said compounds being used as stabilizers for oils and greases based on perfluoropolyethers.    Patent Citation 0003: EP 1219629 A (MATSURAMA OIL RESEARCH COMPANY). Jul. 3, 2002.relates to a phosphazene compound complying with formula here below:A-OCH2CF2O(CF2CF2O)p(CF2O)qCF2CH2O-Awherein A is a group of formula:
wherein R is a hydrogen atom, C1-4 alkyl, C1-4 alkoxy, haloalkyl, aryl, substantially aryl, aryloxy or substituted aryloxy, and p and q are a real number of 1 to 30, said compounds being useful to be used in lubricants for recording media such as hard disks or metal vapor-deposited tapes of video tape recorders or digital video cassettes.
Also, have been described in the past    (Patent Citation 0004: EP 0287892 A (HITACHI METALS). Oct. 26, 1988.) synthetic lubricants for magnetic media complying with formula (B) here below:
wherein n represents an integer of 3 to 10, and Rf and Rf′ represent one or two groups selected from the following groups:    Y(C3F6O)1—CFYCH2O—    Y(C3F6O)1—(CF2O)m—CFYCH2O—    Y(C2F4O)1—(CF2O)m—CFYCH2O—    Y(CF2)1-1—C2H4O—    Y(CF2)1-1—CH2O—    H(CF2)1-1—CH2O—where 1 represents 3 to 250, m 1 to 250, and Y one selected from the group consisting of F—, CF3—, C2F5—, CF3O—, C2F5O— and C3F7O—. Said lubricating agents are endowed with improved adhesion properties to the surface of inorganic materials such as metal, carbon, ceramic, glass. These lubricants are not suggested to be used as anti-wear additives for oils and greases.
Moreover,    Patent Citation 0005: EP 1336614 A (SOLVAY SOLEXIS S.P.A.). Aug. 20, 2003. discloses cyclic phosphazene compounds comprising one or more cyclic moiety of formula:
having bound to all the phosphorus atoms substituents comprising (per)fluoroalkyloxychains having a number averaged molecular weight in the range 280-5000 and end groups of the —OCF2X, —OC2F4X, —OC3F6X type, wherein X═F, Cl, H, wherein said cyclic phosphazenes are suitable for being used as additives for perfluoropolyether oils and greases.    Non Patent Citation 0001: MACCONE, P. New additives for fluorinated lubricants. 70th NLGI Annual Meeting, Hilton Head Island, S.C. (Oct. 25-29, 2003), no. #318.discloses, inter alia, additives for fluorinated oils and greases complying with formula (A) here below:

Nevertheless, the phosphazene compounds of the prior art, even if effective in reducing the wear and increasing upper operating temperature of perfluoropolyether oils and greases, possess a moderate solubility/dispersibility in said oils and greases, which can impair their anti-wear performances in corresponding admixture.
There is still a need in the art for antiwear and anticorrosion additives combining outstanding anti-wear properties to suitable solubility and/or dispersibility in perfluoropolyether oils and greases.